Ear-type thermometers that measure body temperature based on detection results from a thermistor, a temperature detection element that detects ambient temperature, and a thermopile comprised of cold junctions and hot junctions, an infrared light detection element that detects infrared light emitted from a temperature measurement site within the aural cavity, both housed in a probe of the thermometer, has become widespread.
The applicant of the present patent application has previously introduced an ear-type thermometer in which a thermistor and a thermopile are each placed at a distance from the opening of a probe, and infrared radiation is guided from the opening of the probe to the thermopile via a light-guiding tube.
Using such configuration, it is possible to reduce the external dimensions of an end portion which is formed to have an opening at the tip of the probe, allowing insertion into the aural cavity. Further, accurate measurement of body temperature with a conventional thermometer is made difficult due to conduction of body temperature when the probe is inserted into the aural cavity. However, by placing a light-guiding tube to intervene as described above, it is possible to make accurate measurement of body temperature even when body heat is conducted through the probe.
Further, according to the ear-type thermometer mentioned above, a separate probe cover which is configured to cover the probe opening as well as the entire probe is provided. This probe cover is formed as a single unit with a flange portion, and is configured to be freely attached and detached using a probe cover attachment tool which attaches to the probe. This arrangement allows the probe cover to be rinsed with water, making it easy to keep the probe clean even when the probe cover gets covered with ear wax or when a large number of unknown patients are examined using the thermometer, improving hygiene (patent reference 1).    [Patent Reference 1] Japanese Patent Laid-Open No. H11-123179
As described above, when removably placing a probe cover configured to cover the probe opening as well as the entire probe using a probe cover attachment tool, it is desirable for hygienic reasons to rinse the probe cover on a regular basis using water.
On the other hand, according to conventional ear-type thermometers, measurement of body temperature by thermopile is performed regardless of whether a probe cover is attached to the probe or not.
When a probe cover is attached to the probe, a significant amount of infrared light is blocked by the probe cover. For this reason, an error in body temperature measurement occurs when compared to a measurement made without using a probe cover on the probe.
However, probe covers used in such fashion eventually show problems in durability after repeated use, which also exerts negative effect on the measurement accuracy.